Improper Access Control in Fabric Bridge

Opis

The product uses a fabric bridge for transactions between two Intellectual Property (IP) blocks, but the bridge does not properly perform the expected privilege, identity, or other access control checks between those IP blocks.

In hardware designs, different IP blocks are connected through interconnect-bus fabrics (e.g. AHB and OCP). Within a System on Chip (SoC), the IP block subsystems could be using different bus protocols. In such a case, the IP blocks are then linked to the central bus (and to other IP blocks) through a fabric bridge. Bridges are used as bus-interconnect-routing modules that link different protocols or separate, different segments of the overall SoC interconnect.

For overall system security, it is important that the access-control privileges associated with any fabric transaction are consistently maintained and applied, even when they are routed or translated by a fabric bridge. A bridge that is connected to a fabric without security features forwards transactions to the slave without checking the privilege level of the master and results in a weakness in SoC access-control security. The same weakness occurs if a bridge does not check the hardware identity of the transaction received from the slave interface of the bridge.

Skutki

• Confidentiality, Integrity, Access Control, Availability

  DoS: Crash, Exit, or Restart; Bypass Protection Mechanism; Read Memory; Modify Memory

Zapobieganie

• Architecture and Design

  Ensure that the design includes provisions for access-control checks in the bridge for both upstream and downstream transactions.

• Implementation

  Implement access-control checks in the bridge for both upstream and downstream transactions.

Przykłady podatności

• CVE-2019-6260 Baseboard Management Controller (BMC) device implements Advanced High-performance Bus (AHB) bridges that do not require authentication for arbitrary read and write access to the BMC's physical address space from the host, and possibly the network [REF-1138].

Słabość nadrzędna

• CWE-284 Improper Access Control

Kiedy powstaje

• Architecture and Design
• Implementation

Dotyczy

Not Language-Specific, Not OS-Specific, Not Architecture-Specific, Processor Hardware, Not Technology-Specific

Źródła

1. CVE-2019-6260: Gaining control of BMC from the host processor — Stewart Smith, 2019
2. aes0_wrapper.sv lines 72 - 78 — 2021
3. clint.sv line 71 — 2021
4. Fix for clint.sv line 78 — 2021